The paper presents the main results of our study on preparation and characterization of conducting biomembranes to be used as solid polymer electrolytes (SPEs). It bases on deoxyribonucleic acid (DNA), glycerol (GLY) and photosensitive chromophores, like Prussian Blue (PB). Its primary application is in fabrication of electrochromic windows. The new SPEs were characterized by UV-Vis and FTIR spectroscopy. They were used in preparation of small electrochromic devices (ECDs). The obtained devices were evaluated by cyclic voltammetry and also by spectroscopic methods. The results show their color change from blue pale to intense blue after application of a direct current (DC) electric field, making the composites very interesting for industrial applications in smart windows.